Nickel complexes acetates

Dimethyl-1,2,4-triazolium iodide with nickel(II) acetate gives the carbene complex l2Ni( 1,4-dimethyl-l,2,4-triazol-5-ylidene)2 (97OM2209). 

During the systematic investigation of the tautomerization of octacthyl porphyrinogen 2110 it was observed that hexahydroporphyrins 22 could be oxidized in the presence of air to bac-teriochlorins 23 and isobactcriochlorins 24 (both tetrahydroporphyrins) on complexation with nickel(II) acetate. 

Stable enolates such as diethyl malonate anions react with allyl sulfones (or acetates) in the presence of nickel complexes to give a mixture of the a- and /-product83. The regioselectivity is generally poor in the nickel-catalyzed reaction, but the molybdenum-catalyzed reaction is selective for alkylation at the more substituted allylic site, thereby creating a quaternary carbon center84. 

In contrast to 4, 2-acetylpyridine iV-methylthiosemicarbazone, 3a, formed yellow-green, paramagnetic, octahedral [Ni(3a)2A2] complexes with nickel(II) chloride and bromide. The neutral form of the ligand was proposed to be NN eoordinated [180]. Brown, paramagnetic [Ni(3a-H)2] was prepared from nickel(II) acetate with NNS coordination, and its d-d spectrum and ligand field... 

Some of these coupling reactions can be made catalytic if hydrogen is eliminated and combines with the anion, thus leaving the nickel complex in the zero-valent state. Allylation of alkynes or of strained olefins with allylic acetates and nickel complexes with phosphites has been achieved (example 38, Table III). 

P.Y.153 is a nickel complex which was introduced to the market in the late 1960s. It produces slightly dull reddish shades of yellow. Although not fast to acids, the pigment may safely be exposed to alkali. It is fast to mineral spirits and alcohols, but only moderately so to aromatic solvents, such as xylene, and to esters, such as ethyl acetate. 

Schrauzer, Mayweg and Heinrich have reported the preparation of the complex 5 from the reaction of aqueous nickel(ll) chloride with a reaction mixture of benzoin in dioxane and phosphorus(V) sulfide. The parent acid and its salts have not been characterized. The only other closed ring complex, 6, was isolated in low yield (3%) subsequent to the reaction of nickel (II) acetate with the mixture resulting from the reaction of 1,3-propanediol with phosphorus(V) sulfide. As for 5, the parent acid and its salts were not... 

The four-coordinate alkyl complex, LNiI(C0)CH3, may coordinate with carbon monoxide to regenerate the five coordinate alkyl species, and this leads to insertion to form Ni-acyl complex. This complex, LNil (CO)(COCH3), can be cleaved either by water yielding acetic acid or by methanol to give methyl acetate. However, in the presence of high iodide concentration formation of acetyl iodide may predominate (29). This step is reversible and can lead to decarbonylation under low carbon monoxide partial pressure. Similar decarbonylations of acyl halides by nickel complexes are known (34). 

The chemistry outlined in Scheme 24 was then put into effect catalytic hydrogenation of the tris-isoxazole (302) and recyclization with triethylamine gave a tricyclic ligand which was chelated with nickel ions to give (303). Introduction of the fourth nitrogen atom was accomplished by treatment of (303) with ammonium acetate, giving (304). Treatment with cyanide removed the nickel ion which was then replaced with zinc(II) to give (305). The reasons for this transmetallation step were two-fold firstly, zinc(II) corrins, as shown by Eschenmoser, can be readily demetallated, and this fact opens up many options later in the synthesis, but secondly, and more importantly, Eschenmoser s photochemical cyclization of seco-corrins (see Section 3.07.3.4.2.3) does not proceed with nickel complexes of seco-corrins, whereas zinc(II) seco-corrins can be cyclized in almost quantitative yield... 

Complexes of general formula NiL2(NPr2)2 have been obtained by the reaction in ethanol-water mixture of the diol ligand and nickel(II) acetate in alkaline media (tetra-n-propylammonium hydroxide or ammonia).1600... 

The neutral complexes Nil or NiL2B2 (B = py or ibipy) have been conveniently synthesized by reacting the quinone ligand and Ni(CO)4 in apolar solvents (n-pentane, n-hexane, benzene).1 0,1601 The use of anaerobic conditions gives the best results. In one case, that of Ni(C6H402)2, the complex was obtained by the peroxodisulfate oxidation of an aqueous solution of nickel(II) acetate and pyrocatechol. 

Nickel(II) complexes with simple carboxylate anions have been well known for a long time,1715 and nickel(II) acetate tetrahydrate is one of the most thoroughly studied compounds. Selected examples of nickel(II) complexes with carboxylate anions are shown in Table 85. The carboxylato complexes are high-spin octahedral with few exceptions. 

The reaction of ammonium polysulfide with nickel(II) acetate in MeOH solution gave the black diamagnetic square planar complex [Ni(S4)2](NEt4)2 (266) which contains the S4 anion as the unique ligand.1940... 

Most nickel(II) complexes with the various Schiff bases derived from salicylaldehyde and different amines have usually been easily prepared by three general methods (i) the reaction of a nickel(II) salt, usually hydrated nickel(II) acetate, with the preformed Schiff base using water, EtOH, MeOH or their mixtures as reaction medium (ii) the condensation reaction of bis(salicylaldehydato)nickel(II) with the appropriate amine in refluxing EtOH or H20/EtOH mixture (iii) the template reaction of the aldehyde with the appropriate amine in the presence of a nickel salt. In Table 97 the formulas, synthetic methods and some physicochemical properties for a number of nickel(II) salicylaldiminato complexes are reported. Examples of dinuclear complexes formed with Schiff bases are specifically reported in Section 50.5.8.5. 

Copper and nickel complexes of the tridentate l-(2-carboxyphenyl)-3,5-diphenyl- (169 X = C02 R = R = Ph) and 1-(2-hydroxyphenyl)-3,5-diphenyl-(169 X = 0 R = R = Ph) formazans were prepared118 by the interaction of the formazan and the appropriate metal acetate in alcohol and were assigned the three-coordinate structures (170 X = O, C02 R = R = Ph M = Ni, Cu) since the diamagnetic nickel complexes were found to be unimolecular in benzene solution. Treatment of the nickel complex (170 X = O, R = R = Ph M = Ni) with pyridine gave a violet crystalline adduct which was assigned the four-coordinate structure (171 X = O R = R = Ph M = Ni). A product similar to the latter could not be obtained from the nickel complex of l-(2-carboxyphenyl)-3,5-diphenylformazan but nickel complexes of this type were obtained from both l-(2-hydroxyphenyl)- (169 X = O, R = CN R = Ph) and l-(2-carboxyphenyl)- (169 X = C02 R = CN R = Ph) 3-cyano-5-phenylformazans. In all three cases a considerable shade change occurred on going from the three-coordinate complex to the pyridine adduct. 

The monohydrazones of a-diketones react with acetone and nickel(II) acetate to give azine complexes (82), which can be converted to macrocyclic complexes by reaction with 1,2-diamino-ethane, but not 1,3-diaminopropane (Scheme 34).179-181... 

In a similar manner, nickel(li) has the correct ionic radius for the bonding cavity of the fourteen-membered ring, tetraazamacrocycle 6.28. The reaction of 6.29 with nickel(n) acetate in the presence of base gives the nickel(n) complex of 6.28 (Fig. 6-28). This is an example of a template reaction that involves a nucleophilic displacement as the ring-formation process. 

Figure 6-29. The condensation of 6.31 with glyoxal in the presence of nickel(n) acetate gives the nickel(ii) complex of 6.30. In the product, the nickel(n) ion is actually seven co-ordinate with two additional axial solvent molecules which are not shown.

Copper Complexes. The preparation of copper and nickel complexes of tridentate metallizable azo and azomethine dyes is easily carried out in aqueous media with copper and nickel salts at pH 4-7 in the presence of buffering agents such as sodium acetate or amines. Sparingly water soluble precursors can be metallized in alkaline medium at up to pH 10 by using an alkali-soluble copper tetram(m)ine solution as coppering reagent, which is available by treating copper sulfate or chloride with an excess of ammonia or alkanolamines [3],... 

The bromination of complexes of the type (131) with N-bromosuccinimide in acetonitrile produces substances with two bromine atoms per molecule.576 The bromi-nated complexes are planar, diamagnetic non-electrolytes, and n.m.r. spectra are consistent with the substitution having occurred at the positions marked. The free ligands, R = H, can be brominated and on reaction with nickel(n) acetate the same complex results.576... 

A useful spot test utilizes the fact that a suspension of red nickel dimethylglyoxime in water when treated with a neutral or acetic acid solution of a palladium salt yields the yellow palladium dimethylglyoxime, which is sparingly soluble in dilute acids. The test is best performed with dimethylglyoxime paper the latter is prepared as follows. Immerse drop-reaction paper in a 1 per cent alcoholic solution of dimethylglyoxime, dry, then immerse again in a solution of 05m nickel chloride rendered barely ammoniacal. The nickel complex precipitates wash thoroughly with water, immerse in alcohol and dry. 

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